github.com/fjballest/golang@v0.0.0-20151209143359-e4c5fe594ca8/src/syscall/exec_linux_test.go (about)

     1  // Copyright 2015 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  // +build linux
     6  
     7  package syscall_test
     8  
     9  import (
    10  	"io/ioutil"
    11  	"os"
    12  	"os/exec"
    13  	"strings"
    14  	"syscall"
    15  	"testing"
    16  )
    17  
    18  // Check if we are in a chroot by checking if the inode of / is
    19  // different from 2 (there is no better test available to non-root on
    20  // linux).
    21  func isChrooted(t *testing.T) bool {
    22  	root, err := os.Stat("/")
    23  	if err != nil {
    24  		t.Fatalf("cannot stat /: %v", err)
    25  	}
    26  	return root.Sys().(*syscall.Stat_t).Ino != 2
    27  }
    28  
    29  func whoamiCmd(t *testing.T, uid, gid int, setgroups bool) *exec.Cmd {
    30  	if _, err := os.Stat("/proc/self/ns/user"); err != nil {
    31  		if os.IsNotExist(err) {
    32  			t.Skip("kernel doesn't support user namespaces")
    33  		}
    34  		t.Fatalf("Failed to stat /proc/self/ns/user: %v", err)
    35  	}
    36  	if isChrooted(t) {
    37  		// create_user_ns in the kernel (see
    38  		// https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/kernel/user_namespace.c)
    39  		// forbids the creation of user namespaces when chrooted.
    40  		t.Skip("cannot create user namespaces when chrooted")
    41  	}
    42  	// On some systems, there is a sysctl setting.
    43  	if os.Getuid() != 0 {
    44  		data, errRead := ioutil.ReadFile("/proc/sys/kernel/unprivileged_userns_clone")
    45  		if errRead == nil && data[0] == '0' {
    46  			t.Skip("kernel prohibits user namespace in unprivileged process")
    47  		}
    48  	}
    49  	// When running under the Go continuous build, skip tests for
    50  	// now when under Kubernetes. (where things are root but not quite)
    51  	// Both of these are our own environment variables.
    52  	// See Issue 12815.
    53  	if os.Getenv("GO_BUILDER_NAME") != "" && os.Getenv("IN_KUBERNETES") == "1" {
    54  		t.Skip("skipping test on Kubernetes-based builders; see Issue 12815")
    55  	}
    56  	cmd := exec.Command("whoami")
    57  	cmd.SysProcAttr = &syscall.SysProcAttr{
    58  		Cloneflags: syscall.CLONE_NEWUSER,
    59  		UidMappings: []syscall.SysProcIDMap{
    60  			{ContainerID: 0, HostID: uid, Size: 1},
    61  		},
    62  		GidMappings: []syscall.SysProcIDMap{
    63  			{ContainerID: 0, HostID: gid, Size: 1},
    64  		},
    65  		GidMappingsEnableSetgroups: setgroups,
    66  	}
    67  	return cmd
    68  }
    69  
    70  func testNEWUSERRemap(t *testing.T, uid, gid int, setgroups bool) {
    71  	cmd := whoamiCmd(t, uid, gid, setgroups)
    72  	out, err := cmd.CombinedOutput()
    73  	if err != nil {
    74  		t.Fatalf("Cmd failed with err %v, output: %s", err, out)
    75  	}
    76  	sout := strings.TrimSpace(string(out))
    77  	want := "root"
    78  	if sout != want {
    79  		t.Fatalf("whoami = %q; want %q", out, want)
    80  	}
    81  }
    82  
    83  func TestCloneNEWUSERAndRemapRootDisableSetgroups(t *testing.T) {
    84  	if os.Getuid() != 0 {
    85  		t.Skip("skipping root only test")
    86  	}
    87  	testNEWUSERRemap(t, 0, 0, false)
    88  }
    89  
    90  func TestCloneNEWUSERAndRemapRootEnableSetgroups(t *testing.T) {
    91  	if os.Getuid() != 0 {
    92  		t.Skip("skipping root only test")
    93  	}
    94  	testNEWUSERRemap(t, 0, 0, false)
    95  }
    96  
    97  func TestCloneNEWUSERAndRemapNoRootDisableSetgroups(t *testing.T) {
    98  	if os.Getuid() == 0 {
    99  		t.Skip("skipping unprivileged user only test")
   100  	}
   101  	testNEWUSERRemap(t, os.Getuid(), os.Getgid(), false)
   102  }
   103  
   104  func TestCloneNEWUSERAndRemapNoRootSetgroupsEnableSetgroups(t *testing.T) {
   105  	if os.Getuid() == 0 {
   106  		t.Skip("skipping unprivileged user only test")
   107  	}
   108  	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), true)
   109  	err := cmd.Run()
   110  	if err == nil {
   111  		t.Skip("probably old kernel without security fix")
   112  	}
   113  	if !os.IsPermission(err) {
   114  		t.Fatalf("Unprivileged gid_map rewriting with GidMappingsEnableSetgroups must fail")
   115  	}
   116  }
   117  
   118  func TestEmptyCredGroupsDisableSetgroups(t *testing.T) {
   119  	cmd := whoamiCmd(t, os.Getuid(), os.Getgid(), false)
   120  	cmd.SysProcAttr.Credential = &syscall.Credential{}
   121  	if err := cmd.Run(); err != nil {
   122  		t.Fatal(err)
   123  	}
   124  }